Background descriptive data, including anthropometrical (age, gender, height, weight) and sociodemographic information (marital status, social support, leisure time, sick-leave, physical activity, occupational background, co-morbidity, hip pain history, former treatment for hip pain / OA), and consumption of analgetics will be collected by questionnaire at inclusion. Outcome measures will cover all functional levels defined by the World Health Organization's (WHO) International Classification of Functioning, Disability, and Health (2002) and will include: